Vesalius arranged his work into seven books.
Book 1: The Bones and Cartilages The first book constitutes about a quarter of the entire collection. It presents Vesalius' observations on human bones and cartilage, which he
collected from cemeteries. It covers the physical appearance of human bones and the differentiation of human bones and cartilage by function. In each chapter Vesalius describes the bones in great detail, explaining their physical qualities in different ways. In the opening chapters, Vesalius "gives general aspects of bones and skeletal organisation, dealing with the differences in texture, strength, and resilience between bone and cartilage; explaining the complex differences between types of joints and reviewing some basic elements of descriptive techniques and terminology." A major theme of this book is whether
Galen described the bones of the human skeleton accurately. When Vesalius lectured on the human skeleton, he also presented the bones of animals to give credibility to Galen's observations. '
De humani corporis fabrica (1543), page 163.
Book 2: The Ligaments and Muscles Here Vesalius describes the structure of the muscles, the agents used in creating movement by the body, and the material used to hold the joints together. Through his observations of butchers cutting meat, he was able to incorporate the skills they used in the dissection of the human body. The order in which to dissect a human body to effectively observe each muscle in the body is laid out. Each illustration displays a deepening view of the human body which can be followed while dissecting a human body. Vesalius also mentions the instruments needed to perform a dissection. Here Vesalius begins to describe how Galen's anatomical descriptions do not match his own observations. In order to show respect to Galen, he suggests Galen's use of anatomical structure is in fact correct, but not for humans. He even continues to describe some of the structures in the way Galen would.
Book 3: The Veins and Arteries, Book 4: The Nerves In Books 3 and 4, Vesalius describes the veins, arteries, and nerves as vessels, but notes their differing physical structure: veins and arteries contains a hollow channel, but nerves do not. Vesalius describes the route by which air travels through the lungs and the heart. He describes this process as "a tree whose trunks divide into branches and twigs". He also describes how the body contains four veins (the portal vein, the venae cavae, the artery-like vein [now understood as the
Pulmonary Vein], and the umbilical vein) and two arteries (the aorta, and the vein-like artery [now understood as the
Pulmonary Artery]) as being the main vessels which branch out into smaller veins and arteries. Vesalius lists some six hundred vessels in his tabulation of arteries, veins and nerves, but fails to mention the smaller vessels located in the hands and feet, the terminal vessels of the cutaneous nerves, or the vessels in the lungs and liver.
Book 5: The Organs of Nutrition and Generation Vesalius gives detailed descriptions of the organs of nutrition, the urinary system, and the male and female reproductive systems. The alimentary and reproductive systems each make up about forty percent of this book, and the description of the renal system and the correct technique for dissecting it makes up the remainder. In the final chapter, the longest chapter of the entire collection, Vesalius gives detailed step-by-step instructions on how to dissect the abdominopelvic organs. In the first half of the book, Vesalius describes the peritoneum, the esophagus, the stomach, the omentum, the intestines and the mesentery. He then goes on to describe the liver, gallbladder, and the spleen. Finally, he describes the kidneys, the bladder, and the ureters. Vesalius was unfamiliar with the anatomy of pregnancy, which lead him to erroneously provide illustrations of a zonary (band-shaped) placenta and fetal membrane in the 1543 edition of
De Fabrica; Vesalius does so relying on Galenic medicine which used canine reproductive organs rather than human female reproductive organs. The illustrations are corrected in the 1555 edition. The new images depict a discoid
placenta and fetal membrane.
Book 6: The Heart and Associated Organs, Book 7: The Brain These books describe the structure and functions of the heart and the organs of respiration, the brain and its coverings, the eye, the organs of sensation, and the nerves of the limbs. A chapter is also devoted to the dissection of the eye. Vesalius describes the organs of the body in great detail by commenting "on the variable strength of the attachment of the pleura to the thoracic walls, the strong attachment of the pericardium to the diaphragm, the shape and orientation of the ventricles of the heart, and the description of the semilunar valves." He closes each book with a chapter on the correct way to dissect the heart and the brain respectively. ==Galen's errors==